Effectiveness of the Anchorage I/M Program

Background: Motor vehicle activity in shopping mall areas is a primary source of carbon monoxide (CO) emissions, posing a potential long-term health risk for workers with sustained exposure. This study aimed to conduct an environmental health risk assessment of CO exposure for traders operating in the Jumbo Supermarket Area of Manado City. Methods: An observational study with a quantitative approach was conducted in July-August 2025. Ambient air CO concentration was measured in real-time using a CO meter at three location points, with purposive sampling of 30 traders. Respondent characteristics, including exposure parameters, were collected via questionnaire. Health risk analysis was performed by calculating the Average Daily Dose (ADD) and Risk Quotient (RQ), following the US EPA (2022) guidelines, where an RQ > 1 indicates an unacceptable non-carcinogenic risk. Results: The mean ambient CO concentration was 1,591.89 µg/m³, which is significantly below the national air quality standard (10,000 µg/m³) set by Indonesian Minister of Health Regulation No. 02 of 2023. The risk assessment yielded average RQ values of 8.38 x 10⁻⁵ for real-time exposure and 1.23 x 10⁻⁵ for lifetime exposure. All calculated RQ values were substantially below the safety threshold of 1. Conclusion: Current CO concentrations in the study area do not exceed regulatory standards and do not pose an unacceptable non-carcinogenic health risk to traders. However, implementing periodic air quality monitoring is recommended to ensure the continued protection of worker health in this environment.

On-road vehicle emissions of carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs) during 1995–2009 in the Atlanta Metropolitan Statistical Area were estimated using the Motor Vehicle Emission Simulator (MOVES) model and data from the National Emissions Inventories and the State of Georgia. Statistically significant downward trends (computed using the nonparametric Theil-Sen method) in annual on-road CO, NOx, and VOC emissions of 6.1%, 3.3%, and 6.0% per year, respectively, are noted during the 1995–2009 period despite an increase in total vehicle distance traveled. The CO and NOx emission trends are correlated with statistically significant downward trends in ambient air concentrations of CO and NOx in Atlanta ranging from 8.0% to 11.8% per year and from 5.8% to 8.7% per year, respectively, during similar time periods. Weather-adjusted summertime ozone concentrations in Atlanta exhibited a statistically significant declining trend of 2.3% per year during 2001–2009. Although this trend coexists with the declining trends in on-road NOx, VOC, and CO emissions, identifying the cause of the downward trend in ozone is complicated by reductions in multiple precursors from different source sectors.Implications:Large reductions in on-road vehicle emissions of CO and NOx in Atlanta from the late 1990s to 2009, despite an increase in total vehicle distance traveled, contributed to a significant improvement in air quality through decreases in ambient air concentrations of CO and NOx during this time period. Emissions reductions in motor vehicles and other source sectors resulted in these improvements and the observed declining trend in ozone concentrations over the past decade. Although these historical trends cannot be extrapolated to the future because pollutant concentration contributions due to on-road vehicle emissions will likely become an increasingly smaller fraction of the atmospheric total, they provide an indication of the benefits of past control measures.

Abstract. Carbon monoxide (CO) emissions influence global and regional air quality and global climate change by affecting atmospheric oxidants and secondary species. We simulate the influence of halving anthropogenic CO emissions globally and individually from 10 regions on surface and tropospheric ozone, methane, and aerosol concentrations using a global chemical transport model (MOZART-4 for the year 2005). Net radiative forcing (RF) is then estimated using the GFDL (Geophysical Fluid Dynamics Laboratory) standalone radiative transfer model. We estimate that halving global CO emissions decreases global annual average concentrations of surface ozone by 0.45 ppbv, tropospheric methane by 73 ppbv, and global annual net RF by 36.1 mW m−2, nearly equal to the sum of changes from the 10 regional reductions. Global annual net RF per unit change in emissions and the 100 yr global warming potential (GWP100) are estimated as −0.124 mW m−2 (Tg CO)−1 and 1.34, respectively, for the global CO reduction, and ranging from −0.115 to −0.131 mW m−2 (Tg CO)−1 and 1.26 to 1.44 across 10 regions, with the greatest sensitivities for regions in the tropics. The net RF distributions show widespread cooling corresponding to the O3 and CH4 decreases, and localized positive and negative net RFs due to changes in aerosols. The strongest annual net RF impacts occur within the tropics (28° S–28° N) followed by the northern midlatitudes (28° N–60° N), independent of reduction region, while the greatest changes in surface CO and ozone concentrations occur within the reduction region. Some regional reductions strongly influence the air quality in other regions, such as East Asia, which has an impact on US surface ozone that is 93% of that from North America. Changes in the transport of CO and downwind ozone production clearly exceed the direct export of ozone from each reduction region. The small variation in CO GWPs among world regions suggests that future international climate agreements could adopt a globally uniform metric for CO with little error, or could use different GWPs for each continent. Doing so may increase the incentive to reduce CO through coordinated policies addressing climate and air quality.

<div class="htmlview paragraph">A kinetic carbon monoxide (CO) emission model is developed to simulate engine out CO emissions for conventional diesel combustion. The model also incorporates physics governing CO emissions for low temperature combustion (LTC). The emission model will be used in an integrated system level model to simulate the operation and interaction of conventional and low temperature diesel combustion with aftertreatment devices. The Integrated System Model consists of component models for the diesel engine, engine-out emissions (such as NOx and Particulate Matter), and aftertreatment devices (such as DOC and DPF). The addition of CO emissions model will enhance the capability of the Integrated System Model to predict major emission species, especially for low temperature combustion.</div> <div class="htmlview paragraph">In this work a CO emission model is developed based on a two-step global kinetic mechanism [<span class="xref">8</span>]. In addition, effect of physical parameters such as start of injection (SOI) and ignition delay are studied and modeled to develop a phenomenological CO emission model. This includes development of a simple spray model to compute amount of fuel missing the bowl in case of PCCI and HCCI type combustion. Results from the spray model are used to simulate the motion of fuel in the cylinder bowl during various stages of combustion. Ignition delay effects are analyzed and modeled to change the activation temperature of CO oxidation reaction to simulate the affect of increasing peak temperatures with advancing SOI. The results from the CO emission model are compared with experimental data from a multi-cylinder conventional diesel engine as well as a single cylinder version of a low temperature combustion diesel engine. For the LTC engine, the start of injection is advanced using two different injection strategies (single and two-step injection). Overall the results show good agreement of the trends between the experiments and model predictions.</div>

Air pollution, particularly from carbon monoxide (CO) in vehicle emissions, poses a health threat to chronically exposed populations, including traders in traditional markets. Bersehati Market in Manado is a shopping center with high vehicle activity, potentially leading to increased ambient CO concentrations. This study aimed to analyze the non-carcinogenic environmental health risks due to CO gas exposure among traders at Bersehati Market. This observational study with an Environmental Health Risk Assessment (EHRA) approach was conducted from March to July 2025. Ambient air samples were measured at three different points and times (morning, afternoon, evening) using a Carbon Monoxide Meter, and exposure characteristics (duration, frequency, length) and anthropometric data were collected from 30 purposively selected trader respondents. Risk analysis was performed by calculating the intake and Risk Quotient (RQ) for both real-time and lifetime (70 years) exposure. The measurement results showed an average CO concentration of 348.67 µg/m³, with the highest concentration of 973 µg/m³ at a morning measurement point. However, all concentrations remained below the threshold set by Indonesian Government Regulation No. 41 of 1999 (30,000 µg/m³). The average real-time intake was 0.018 mg/kg/day, while the lifetime intake was 0.009 mg/kg/day. The highest real-time RQ value was 0.02788 and the highest lifetime RQ was 0.03584. Since all RQ values were < 1, this study concludes that, statistically, CO exposure to traders at Bersehati Market does not yet indicate a significant non-carcinogenic health risk, either under current conditions or in long-term projections. Nonetheless, the long daily exposure duration and fluctuating CO concentrations necessitate ongoing vigilance and monitoring.

<div class="section abstract"><div class="htmlview paragraph">Reactivity Controlled Compression Ignition (RCCI) has demonstrated diesel-like or better brake thermal efficiency with significant reductions in nitrogen oxide (NO<sub>X</sub>) and particulate matter (PM) emissions. Hydrocarbon (HC) and carbon monoxide (CO) emission levels, on the other hand, are higher and similar to those of port-fuel-injected (PFI) gasoline engines. The higher HC and CO emissions combined with the lower exhaust temperatures during RCCI operation present a challenge for current exhaust aftertreatment technologies. The reduction of HC and CO emissions in a lean environment is typically achieved with an oxidation catalyst. In this work, several diesel oxidation catalysts (DOC) with different precious metal loadings were evaluated for effectiveness to control HC and CO emissions from RCCI combustion in a light-duty multi-cylinder engine operating on gasoline and diesel fuels. Each catalyst was evaluated under steady-state engine operation with temperatures ranging from 160 to 260°C. A shift to a higher light-off temperature was observed during the RCCI operation. In addition to the steady-state experiments, the performance of the DOCs were evaluated during multi-mode engine operation by switching from diesel-like combustion at higher exhaust temperature and low HC/CO emissions to RCCI combustion at lower temperature and higher HC/CO emissions. High CO and HC emissions from RCCI generated an exotherm temporary keeping the catalyst above the light-off temperature.</div></div>

Region-specific air pollutants and meteorological parameters influence COVID-19: A study from mainland China

Simplification of the end-alveolar carbon monoxide technique to assess erythrocyte survival

Carbon Monoxide (CO) has become a pressing issue for the recreational marine industry. An increasing number of boating incidents have been linked to CO poisoning caused by emissions from gasoline-powered marine engines. Measurements by the National Institute for Occupational Safety and Health (NIOSH) and the U.S. Coast Guard have confirmed potentially hazardous CO concentrations near many of these engines. The measurements have also shown much lower CO concentrations for Evinrude® two-strbke direct-injected engines. This paper reviews national and international CO emission regulations for marine engines and discusses CO formation and reduction mechanisms. The differences between homogeneous- and stratified-charge combustion systems on CO formation, resulting from design and calibration criteria, are analyzed. The primary driving factors for CO formation under high-load homogeneous operation are driven by a desire to maximize power output and a necessity to control the thermal loading of internal engine components. Part throttle and low-load operation are largely driven by emissions and run-quality requirements. Several distinct advantages for direct-injected engines lead to the formation of significantly lower CO concentrations in the exhaust. The unavoidable over-scavenging of air aids in diluting cylinder-out CO levels. This, combined with high exhaust gas temperatures, can generate a significant post-oxidation effect. The post-oxidation effect was investigated in detail and some engine test results are presented. Stratified operation at low loads with high air-fuel ratios result in CO concentrations up to 100 times less than homogeneous-charge engines.

Long-term trend analysis of CO in the Yongsan district of Seoul, Korea, between the years 1987 and 2013

Scaling relationship between CO pollution and population size over major US metropolitan statistical areas

Breath and ambient (room) carbon monoxide (CO) levels were measured in a random sample of 168 adults in their own homes. The levels of breath CO in the 69 smokers ranged from 3 ppm to over 100 ppm, 74% being above 10 ppm; mean levels in the 99 nonsmokers were lower than in the smokers, 79% being below 6 ppm. In the remaining 21% of nonsmokers with higher breath levels than expected, the ambient CO was also found to be elevated, ranging up to 38 ppm. A close correlation in the nonsmokers was found between the breath and ambient CO levels (r = 0.952, p less than 0.001). The rooms with the elevated ambient CO levels (above 5 ppm) were those which, at the time of testing, were being heated by gas radiant heaters, open fires or stoves. The maximum ambient CO in the rooms of smokers with non CO generating heating was 16 ppm. The results suggest that many people, both smokers and nonsmokers, may be at risk from CO generated by certain domestic heating systems and that nonsmokers are far more likely to be exposed to high levels of CO from these sources than from being in a room with a heavy smoker. Poor ventilation associated with the current trend towards excluding all draughts is likely to exacerbate the situation for both smokers and nonsmokers.

Operation of gas power plants creates emissions of various air pollutants including carbon monoxide with associated health and environmental effects. This study investigated the ground level concentrations of carbon monoxide from units of the 4 MW Gas Power Plants of a leading utility, gas and energy company in Lagos, Nigeria. Air emissions of CO from the gas power plants at the project site were calculated using the emission factors. The AERMOD dispersion modelling tool (version 9.6.1) was used to model ground level concentrations of CO associated with air emissions from the two units of 1364 kW and 774 kW of Gas Power Plants. Three different scenarios involving the gas turbines operations were considered. Scenario 1 and 2 involved the operation of 1364 kW and 774 kW, respectively while scenario 3 involved the simultaneous operation of both gas power plants. The predicted ground level CO concentrations from the three scenarios in all locations considered were within the FMEnv’s limits, though, the ambient CO at the project site in scenario 1, 2 and 3 changed by 2.31%, 1.72%, and 2.68% of limit, respectively. However, sites using gas power plants near communities may further reduced emissions of air pollutants by developing relevant control techniques with continuous monitoring of these emissions at the site. This study also provides stake holders necessary information that can help in making profitable decisions and guidelines in similar situation.

<strong class="journal-contentHeaderColor">Abstract.</strong> Adjoint of the GEOS-Chem model has been widely used to constrain the sources of various atmospheric pollutants. Here we provide an updated version (GC-Adjoint-HEMCO) of the adjoint of GEOS-Chem model to support the MERRA-2 meteorological data and Harmonized Emissions Component (HEMCO) emission inventories. State-of-the-art inventories, such as CEDS (Community Emissions Data System), MIX, NEI2011 (National Emissions Inventory), and GFED4 (Global Fire Emission Database), are supported in GC-Adjoint-HEMCO. We find good agreements in carbon monoxide (CO) emissions from various inventories, chemical sources and sinks, and surface and column CO concentrations between GC-Adjoint-HEMCO and GEOS-Chem (v12-8-1) forward simulations. Furthermore, observing system simulation experiments (OSSE) are employed to evaluate the performance of GC-Adjoint-HEMCO in 4D variational (4D-var) assimilations. We find underestimations by approximately 15 % in the a posteriori anthropogenic CO emissions over North America and Europe due to limited coverage of observations by smoothing the pseudo-CO observations with Measurement of Pollution in the Troposphere (MOPITT) averaging kernels. As an example application of GC-Adjoint-HEMCO, we constrain anthropogenic CO emissions in 2015 by assimilating MOPITT CO observations. The a posteriori anthropogenic CO emission estimates derived in this work match well with Jiang et al. (2017) in North America and Africa but are overestimated in Asia, South America and Australia, which could be associated with the different treatment of MOPITT CO observations over ocean grids and the large differences in CO chemical sources and sinks. The updated model developed in this work is a useful extension of the adjoint of GEOS-Chem model.

Increasing environmental concerns caused by vehicular emissions have intensified the search for the design and development of non-noble metal catalysts for catalytic converter devices as potential replacements for conventional Pt-, Pd-, and Rh-based noble metal catalysts. This research highlights the development and evaluation of an alternative to conventional catalysts through the synthesis of non-noble metal perovskite-based catalysts and the design modification of a catalytic converter. A non-noble metal catalyst, La 0 . 8 Sr 0 . 2 Co 0 . 8 Fe 0 . 2 O 3 (LSCF), was synthesized by co-precipitation, coated onto a ceramic monolith of a catalytic converter, and examined for effectiveness under petrol fuel laboratory test setup. The synthesized catalyst was also analyzed using SEM, XRD, and EDX to study surface morphology and confirm the crystal structure. The catalytic converter housing assembly was modified by integrating design modifications and analyzed through computational simulations to investigate velocity profile, pressure distribution, and reaction behavior. Among the three catalytic converter design configurations with diffuser cone angles of 8°, 10°, and 14°, the first was selected as it showed a favorable gas flow pattern, pressure distribution, and velocity profile. The entire module was then experimentally evaluated on a petrol fuel laboratory test setup to assess emission performance under varying loads and speeds. Experimental emission tests revealed a significant reduction in hydrocarbon (HC) and carbon monoxide (CO) emissions compared to engines without a catalytic converter. The results demonstrate that the synthesized La 0 . 8 Sr 0 . 2 Co 0 . 9 Fe 0 . 1 O 3 -δ non-noble metal catalyst, combined with the modified catalytic converter design, effectively reduces vehicular emissions and provides an alternative and practical approach to noble metal catalysts. A noticeable reduction in CO and HC exhaust emissions was achieved using the LSCF catalyst for an automotive catalytic converter.